Heating element of a printhead having resistive layer over conductive layer

ABSTRACT

10006488 A heating element of a printhead has a conductive layer deposited over a substrate, and a resistive layer deposited over and in electrical contact with the conductive layer.

FIELD OF THE INVENTION

[0001] The present invention relates to printheads, such as those usedin inkjet cartridges and the like.

BACKGROUND OF THE INVENTION

[0002] Generally, thermal actuated printheads use resistive elements orthe like to achieve ink expulsion. A representative thermal inkjetprinthead has a plurality of thin film resistors provided on asemiconductor substrate. A top layer defines firing chambers about eachof the resistors. Propagation of a current or a “fire signal” throughthe resistor causes ink in the corresponding firing chamber to be heatedand expelled through the corresponding nozzle.

[0003] To form the resistors, a resistive material is deposited over aninsulated substrate, and a conductive material is deposited over theresistive material. The conductive material is photomasked and wetetched to form conductor traces and a beveled surface adjacent aresistor. However, due to the difficultly in controlling the wet etchingprocess, substantially inconsistent resistor lengths (gap in theconductor line) and beveled angles result. A dry etch is generally notused to etch the conductor traces because dry etch selectivity oftypical conductor to resistor materials is poor.

[0004] The resistive material is photomasked and etched to formresistors. A passivation layer is deposited over the conductor traces.The passivation layer is often susceptible to pinhole defects, and wetchemistry, including those used in subsequent wet processing and inks,may travel through the defects in the passivation layer to the conductorlayer. The conductor layer thereby begins to corrode.

SUMMARY OF THE INVENTION

[0005] In the present invention, a heating element of a printhead has aconductive layer deposited over a substrate, and a resistive layerdeposited over and in electrical contact with the conductive layer.

[0006] Many of the attendant features of this invention will be morereadily appreciated as the same becomes better understood by referenceto the following detailed description and considered in connection withthe accompanying drawings in which like reference symbols designate likeparts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 illustrates a perspective view of a print head cartridge ofthe present invention;

[0008]FIG. 2 illustrates a cross-sectional view of an embodiment of theprinthead of FIG. 1 shown through section 2-2;

[0009]FIG. 3 is a flow chart illustrating an embodiment of the processof forming the resistor over the conductor traces;

[0010]FIG. 4a illustrates a perspective view of an embodiment of theprinthead formation after the conductor traces have been etched;

[0011]FIG. 4b illustrates a perspective view of an embodiment of theprinthead formation after the resistors have been etched;

[0012]FIG. 5 illustrates a partial cross-sectional view of the formationof FIG. 4b through section 5-5;

[0013]FIG. 6 illustrates a cross-sectional view of the formation of FIG.4b through section 6-6;

[0014]FIG. 7 illustrates another embodiment of the cross-sectional viewof the formation of FIG. 4 through section 6-6;

[0015]FIG. 8 illustrates another embodiment of the cross-sectional viewof the formation of FIG. 4 through section 6-6;

[0016]FIG. 9a illustrates a layer of photoresist over the conductivelayer as part of the process of bevel definition;

[0017]FIG. 9b illustrates FIG. 9a after exposing the photoresist tolight through a halftone mask;

[0018]FIG. 10 is a half-tone mask; and

[0019]FIG. 11 is another half-tone mask.

DETAILED DESCRIPTION

[0020]FIG. 1 is a perspective view of an inkjet cartridge 10 with aprinthead 14 of the present invention. FIG. 2 illustrates across-sectional view through section 2-2 of FIG. 1. In FIG. 2, a thinfilm stack is applied over a substrate 28. A slot region 120 is shownthrough the thin film stack and the substrate 28. One method of formingthe drill slot is abrasive sand blasting. A blasting apparatus uses asource of pressurized gas (e.g. compressed air) to eject abrasiveparticles toward the substrate coated with thin film layers to form theslot. The particles contact the coated substrate, causing the formationof an opening therethrough. Abrasive particles range in size from about10-200 microns in diameter. Abrasive particles include aluminum oxide,glass beads, silicon carbide, sodium bicarbonate, dolomite, and walnutshells.

[0021] In one embodiment, the substrate is a monocrystalline siliconwafer. The wafer has approximately 525 microns for a four-inch diameteror approximately 625 microns for a six-inch diameter. In one embodiment,the silicon substrate is p-type, lightly doped to approximately 0.55ohm/cm.

[0022] Alternatively, the starting substrate may be glass, asemiconductive material, a Metal Matrix Composite (MMC), a CeramicMatrix Composite (CMC), a Polymer Matrix Composite (PMC) or a sandwichSi/xMc, in which the x filler material is etched out of the compositematrix post vacuum processing. The dimensions of the starting substratemay vary as determined by one skilled in the art.

[0023] In one embodiment, a capping layer 32 is deposited or grown overthe substrate 28. In one embodiment, the layer 32 covers and seals thesubstrate 28, thereby providing a gas and liquid barrier layer. Becausethe capping layer is a barrier layer, fluid is substantially restrictedfrom flowing into the substrate 28. Capping layer 32 may be formed of avariety of different materials such as silicon dioxide, aluminum oxide,silicon carbide, silicon nitride, and glass (PSG). In one embodiment,the use of an electrically insulating dielectric material for thecapping layer also serves to electrically insulate substrate 28. In oneembodiment, the capping layer 32 is a thermal barrier of the substratefrom the resistor. The capping layer may be formed using any of avariety of methods known to those of skill in the art such as thermallygrowing the layer, sputtering, evaporation, and plasma enhanced chemicalvapor deposition (PECVD). The thickness of capping layer may be anydesired thickness sufficient to cover and seal the substrate. Generally,the capping layer has a thickness of up to about 1 to 2 microns.

[0024] In one embodiment, the layer 32 is a phosphorous-doped (n+)silicon dioxide interdielectric, insulating glass layer (PSG) depositedby PECVD techniques. Generally, the PSG layer has a thickness of up toabout 1 to 2 microns. In one embodiment, this layer is approximately 0.5micron thick and forms the remainder of the thermal inkjet heaterresistor oxide underlayer. In another embodiment, the thickness range isabout 0.7 to 0.9 microns.

[0025] In another embodiment, the capping layer 32 is field oxide (FOX)that is thermally grown on the exposed substrate 28. The process growsthe FOX into the silicon substrate as well as depositing it on top toform a total depth of approximately 1.3 microns. Because the FOX layerpulls the silicon from the substrate, a strong chemical bond isestablished between the FOX layer and the substrate.

[0026] In one embodiment, a layer 30 is deposited or grown over thecapping layer 32. In one embodiment, the layer 30 minimizes junctionspiking and electromigration. In one embodiment, the layer 30 is one oftitanium nitride, titanium tungsten, titanium, a titanium alloy, a metalnitride, tantalum aluminum, and aluminum silicone.

[0027] In one embodiment, layer 32 is deposited over or grown directlyonto the substrate 28. In another embodiment, there are layers (notshown), in addition to layer 30 and layer 32, that are deposited overthe substrate. These layers are composed of materials chosen from thelayers 30 and 32 described above.

[0028] In one embodiment, a conductive layer 114 is formed by depositingconductive material over the layer 30. The conductive material is formedof at least one of a variety of different materials including aluminum,aluminum with about ½% copper, copper, gold, and aluminum with ½%silicon, and may be deposited by any method, such as sputtering andevaporation. Generally, the conductive layer has a thickness of up toabout 1 to 2 microns. In one embodiment, sputter deposition is used todeposit a layer of aluminum to a thickness of approximately 0.5 micron.

[0029] The conductive layer 114 is patterned and etched as described inmore detail below with respect to steps 210 and 220 of FIG. 3. Aconductor trace width 16 and a resistor length 17, as shown in FIG. 4a,is defined by the etch of the conductive layer. (The resistor length isa gap or opening in the conductive line). At this point, the layer 30,as shown in FIG. 4a, or possibly even layer 32, as shown in FIG. 5, isexposed along the resistor length 17 (or opening) in between the tracesdue to etching. At opposite ends of the defined resistor length 17, theconductive material 114 has a beveled surface 126 defined as describedin more detail below. The conductor traces have a top surface 128, twoopposing side surfaces 130, and the end beveled surface 126.

[0030] After forming the conductor traces, a resistive material 115 isdeposited over the etched conductive material 114, as shown in FIG. 2(step 240 of FIG. 3). The resistive material is etched to form resistorshaving the resistor length 17, as described in more detail below withrespect to steps 250 and 260 of FIG. 3. The width of the resistorsacross the conductor traces is a cap width 18, which varies with theembodiment, as described in more detail below with regard to FIGS. 6, 7and 8. There is also a resistor width of the gap 17 that is the samelength as the cap width, in one embodiment. Alternatively, the resistorwidth is different than the cap width. In one embodiment, the resistivematerial encapsulates the conductor traces. In one embodiment, sputterdeposition techniques are used to deposit a resistive material layer oftantalum aluminum 115 composite across the etched conductor traces. Thecomposite has a resistivity of approximately 30 ohms/square. Typically,the resistor layer has a thickness in the range of about 500 angstromsto 2000 angstroms. However, resistor layers with thicknesses outsidethis range are also within the scope of the invention.

[0031] A variety of suitable resistive materials are known to those ofskill in the art including tantalum aluminum, nickel chromium, andtitanium nitride, which may optionally be doped with suitable impuritiessuch as oxygen, nitrogen, and carbon, to adjust the resistivity of thematerial. The resistive material may be deposited by any suitable methodsuch as sputtering, and evaporation.

[0032] As shown in the embodiment of FIG. 2, an insulating passivationlayer 117 is formed over the resistors and conductor traces to preventelectrical charging of the fluid or corrosion of the device, in theevent that an electrically conductive fluid is used. Passivation layer117 may be formed of any suitable material such as silicon dioxide,aluminum oxide, silicon carbide, silicon nitride, and glass, and by anysuitable method such as sputtering, evaporation, and PECVD. Generally,the passivation layer has a thickness of up to about 1 to 2 microns.

[0033] In one embodiment, a PECVD process is used to deposit a compositesilicon nitride/silicon carbide layer 117 to serve as componentpassivation. This passivation layer 117 has a thickness of approximately0.75 micron. In another embodiment, the thickness is about 0.4 microns.The surface of the structure is masked and etched to create vias formetal interconnects. In one embodiment, the passivation layer places thestructure under compressive stress.

[0034] In one embodiment, a cavitation barrier layer 119 is added overthe passivation layer 117. The cavitation barrier layer 119 helpsdissipate the force of the collapsing drive bubble left in the wake ofeach ejected fluid drop. Generally, the cavitation barrier layer has athickness of up to about 1 to 2 microns. In one embodiment, thecavitation barrier layer is tantalum. The tantalum layer 119 isapproximately 0.6 micron thick and serves as a passivation,anti-cavitation, and adhesion layer. In one embodiment, the cavitationbarrier layer absorbs energy away from the substrate during slotformation. In this embodiment, tantalum is a tough, ductile materialthat is deposited in the beta phase. The grain structure of the materialis such that the layer also places the structure under compressivestress. The tantalum layer is sputter deposited quickly thereby holdingthe molecules in the layer in place. However, if the tantalum layer isannealed, the compressive stress is relieved.

[0035] In one embodiment, a top (or barrier) layer 124 is deposited overthe cavitation barrier layer 119. In one embodiment, the barrier layerhas a thickness of up to about 20 microns. In one embodiment, thebarrier layer 124 is comprised of a fast cross-linking polymer such asphotoimagable epoxy (such as SU8 developed by IBM), photoimagablepolymer or photosensitive silicone dielectrics, such as SINR-3010manufactured by ShinEtsu™.

[0036] In another embodiment, the barrier layer 124 is made of anorganic polymer plastic which is substantially inert to the corrosiveaction of ink. Plastic polymers suitable for this purpose includeproducts sold under the trademarks VACREL and RISTON by E. I. DuPont deNemours and Co. of Wilmington, Del. The barrier layer 124 has athickness of about 20 to 30 microns.

[0037] In one embodiment, the barrier layer 124 includes a firingchamber 132 from which fluid is ejected, and a nozzle orifice 122associated with the firing chamber through which the fluid is ejected.The fluid flows through the slot 120 and into the firing chamber 132 viachannels formed in the barrier layer 124. Propagation of a current or a“fire signal” through the resistor causes fluid in the correspondingfiring chamber to be heated and expelled through the correspondingnozzle 122. In another embodiment, an orifice layer having the orifices122 is applied over the barrier layer 124.

[0038] As shown more clearly in the printhead 14 of FIG. 1, the nozzleorifices 122 are arranged in rows located on both sides of the slot 120.In one embodiment, the nozzle orifices, and corresponding firingchambers are staggered from each other across the slot. In FIG. 2, afiring chamber in the printhead that is staggered across the slot fromthe firing chamber 132 is shown in dashed lines.

[0039] The flow chart of FIG. 3 illustrates an embodiment of the processof forming the heating element of the printhead. After depositing theconductive material in step 200, the conductive material is photomasked,such as by photolithography, and etched to form the conductor traces. Inone embodiment, photoresist material is deposited in step 210 over theconductive material. The photoresist material is exposed to lightthrough a mask and developed to form a pattern over the conductivematerial, as described in more detail below with regard to FIGS. 9a, 9b, 10 and 11. Conductive material that is not covered by the photoresistmaterial is removed using a dry plasma etch in step 220, which is aconventional gaseous etch technique.

[0040]FIG. 4a illustrates one embodiment where the formation after theconductor trace width 16 and the resistor length or gap 17 have beenetched. The beveled surface 126 of the conductor trace is defined asdescribed in the embodiments below. In another embodiment, only theresistor length or gap 17 is formed in step 220. The trace width and capwidth are then formed together in step 260 to look like the embodimentshown in FIG. 8.

[0041] The photoresist material is then stripped in step 230 before theresistive material is deposited in step 240. Similar to step 210, theresistive layer 114 is patterned and etched in step 250, as shown inFIG. 4b. Thereby, the cap width 18 of the resistive material and theconductor terminations (not shown) are defined. In one embodiment, thephotoresist material is deposited, masked, exposed and developed to thepattern over the resistive material in step 250, as described in moredetail below. The resistive layer and photoresist material is thenetched in step 260. In one embodiment, the resistive layer is dryetched. In another embodiment, the resistive layer is wet etched. Thephotoresist material deposited over the resistive layer is removed instep 270 before the passivation layer is deposited.

[0042]FIG. 5 illustrates a cross-sectional view of the resistivematerial 115 deposited over the opening (or resistor length 17) and thebeveled surfaces 126 of the etched conductive layer 114. FIG. 6illustrates a cross-sectional view of the width of the conductor traceswith the etched resistive material 115 deposited thereover. FIGS. 7 and8 illustrate other embodiments as alternatives to the embodiment shownin FIG. 6.

[0043] For FIG. 5, the photoresist material in step 250 covers theresistor and conductor terminations (not shown). The photoresistmaterial pattern in step 250 varies for defining the formations of FIGS.6, 7, and 8. For FIGS. 6 and 7, the photoresist material in step 250 isin a pattern that covers the conductor trace. For FIG. 8, thephotoresist material in step 250 is in a pattern that defines the topsurface 128 of the conductor trace. During the etch step 260, the areathat is not covered with the photoresist material is etched away.

[0044] In one embodiment, as shown in FIG. 5, the layer 30 is etchedaway in step 220 with the conductive layer in the area defining theresistor length 17. In one embodiment, the layer 30 is conductive andelectrically conducts under the opening in the conductor traces, if notremoved. In another embodiment, additionally the layer 32 and/or thesubstrate 28 are partially etched in the gap area (17). In yet anotherembodiment, the layer 30 is not etched away with the conductive layer.

[0045] In one embodiment, the end beveled surface 126 has an angle ofabout 35 to 55 degrees with the substrate, as shown in FIG. 5. Inanother embodiment, the end beveled surface has an angle of about 45degrees with the substrate. As shown, the beveled surface 126 issubstantially smooth from the dry etch. The horizontal length of thebeveled surface 126 is about ½ to 3 microns. In one embodiment, thehorizontal length depends upon the drop weight of the print cartridges.For higher drop weights, the more slope (or higher length) is desired.

[0046] In FIGS. 6 and 8, the side surfaces 130 are substantiallyvertical, so that conductor traces are able to be etched closertogether, thereby increasing the die separation ratio. In oneembodiment, the side surfaces 130 of the conductor traces are dry etchedin the process described herein. In one embodiment, the side surfaces130, have an angle of about 60 to 80 degrees with the substrate. Inanother embodiment, the side surfaces have an angle of about 70 degreeswith the substrate. The side surfaces 130 are formed as describedherein.

[0047] In FIG. 7, the side surfaces 130 a are sloped more than the sidesurfaces 130 shown in FIGS. 6 and 8. The side surfaces 130 a have anangle of about 35 to 55 degrees, or about 45 degrees, with thesubstrate. In one embodiment, the angle of the side surfaces 130 a issubstantially similar to the angle of the beveled surface 126. Inanother embodiment, the angle of the side surfaces 130 a is differentthan the angle of the beveled surface 126. In one embodiment, the sidesurfaces 130 a are formed using the photomasking and dry etchingtechniques, as described herein. In another embodiment, the sidesurfaces are formed in a manner substantially similar to forming the endbeveled surfaces 126, as described below.

[0048] In FIGS. 6 and 7, the cap width 18 of the resistive material isgreater than the width 16 of the conductor trace. In this embodiment,the resistive material encapsulates the conductor traces. In theembodiment where the layer 30 is formed of the same material as theresistive material 115, the conductor layer 114 is substantiallycompleted encapsulated. The resistive material encapsulating the sidesurfaces 130 of the conductor traces aid in protecting the traces fromcorrosion due to wet chemistry, including those fluids used insubsequent wet processing and inks.

[0049] In FIG. 8, the cap width 18 of the resistive material covers thetop surface 128 of the conductor traces, the width 16. The side surfaces130 are not covered with the resistive material in this embodiment. Thepassivation layer 117, when deposited, is in direct contact with theside surfaces and aid in protecting the conductor traces from corrosion.

[0050] In one embodiment of step 210 of FIG. 3, the conductor traces andthe beveled surfaces 126 (and in some embodiments, the side surfaces 130a of FIG. 7) are defined using masking techniques illustrated in FIGS.9a, 9 b, and 10. The sloped end surfaces 126 and the substantiallyvertical side walls 130 are formed using a half-tone mask 136, as shownin FIG. 10. In some embodiments, a half-tone mask 137 (FIG. 11) that issimilar to the mask 136 is used to form both the sloped end surfaces 126and the sloped side surfaces 130 a. The masks 136 and 137 are describedin more detail below.

[0051]FIG. 9a illustrates a layer of photoresist material 134 over theconductive layer 114 as part of the process of bevel definition. Thephotoresist material 134 is a chemical substance rendered insoluble byexposure to light. The unexposed areas are washed away. After exposingthe photoresist material 134 to light through the mask 136, theformation in cross-section is illustrated in FIG. 9b. The photoresistmaterial 134 is sloped as shown in FIG. 9b after step 210 is performed.The photoresist material 134 along with the conductor layer 114 of FIG.9b is then etched using a dry etch in step 220. After etching, thebeveled surfaces 126 are defined as shown in FIG. 5. In addition, thegap or resistor length 17, and the side surfaces 130, as shown in FIGS.6 and 8, are defined. In some embodiments the sloped side surfaces 130 aof FIG. 7 are also defined using this photomask technique, but using themask 137.

[0052] The mask 136 has three areas, area 138, gradiated area 140, andopen area 142. The area 138 is substantially non-transparent. In oneembodiment, this area 138 is made of chrome. When this area of the maskis placed over the photoresist material 134, and the photoresistmaterial is exposed to light, the area under 138 is unexposed and can bewashed away. The open area 142 is an opening in the mask through whichthe light exposing the photoresist material passes through. Thephotoresist material under the open area 142 substantially hardens (oris rendered insoluble) in response to the light. The area 140 isgradiated. The area 140 gradually moves from being substantiallynontransparent to being substantially transparent when moving away fromarea 138 and closer to area 142. The photoresist material that isexposed to the light under the area 140 forms a slope as shown in FIG.9b.

[0053] In an alternative embodiment, the photoresist material is apositive photoresist material. Opposite to the negative photoresistmaterial described above, the positive photoresist material that is notexposed to light is rendered insoluble, while the material that isexposed to light is washed away. A mask used in this embodiment that issimilar to mask 136 has, for example, areas 138 and 142 switched torender the same shape of material 134 in FIG. 9b. Similarly, the area140 gradually moves from being substantially non-transparent to beingsubstantially transparent when moving away from area 138 and closer toarea 142.

[0054] The mask 137 is similar to the mask 136 except that the mask 137has a u-shaped gradiated area 140 that surrounds the open area 142. Theu-shaped gradiated area 140 is in between the open area 142 and the area138. The u-shaped forms photoresistive material in a substantiallytrapezoidal cross-section over the conductive material. After thephotoresistive material is etched, the sloped end surfaces 126 and thesloped side surfaces 130 a are formed. In one embodiment, the u-shapedarea 140 is formed such that the surfaces 126 and 130 a have differentdimensions and angles. In another embodiment, the u-shaped area 140 issubstantially of a uniform width and the surfaces 126 and 130 a havesubstantially similar dimensions and angles.

[0055] In another embodiment of step 210, the conductor traces and thebeveled surfaces 126 (and in some embodiments, the side surfaces 130 aof FIG. 7) are defined using a technique of intentionally misfocused orindefinite exposure of the photoresist material 134 of FIG. 9a to light.The misfocused light functions in a manner similar to the mask 136. Inone embodiment, the misfocused light is used in conjunction with a maskhaving the sections 138 and 142 (not shown). To form the sloped areas ofthe photoresist material, the light is substantially clearly focused inareas where the photoresist material is rendered insoluble, andgradually changes along the photoresist material surface to beingsubstantially misfocused where the photoresist material is to beremoved. The sloped sections of photoresist material as shown in FIG. 9bare thereby formed. The beveled surfaces 126 are then defined byetching. Additionally, in another embodiment, the photoresist materialis sloped over the width of the conductive material using misfocusedlight to form the side surfaces 130 a of FIG. 7.

[0056] In another embodiment of step 210, the sloped end surfaces 126and the sloped side surfaces 130 a shown in FIG. 7 are formed using apre-etch hard bake technique. In the pre-etch hard bake technique, thephotoresist material 134 of FIG. 9a is masked, exposed to light anddeveloped in a pattern to form the conductor traces. Then thephotoresist material is exposed to the hard bake (a high temperature)until the photoresist flows into a substantially trapezoidalcross-section. The formation is then etched in step 220 to form thesloped side surfaces 130 a and the beveled surfaces 126, as shown inFIGS. 5 and 7. In this embodiment, the surfaces 126 and 130 a havesubstantially similar dimensions due to the flowing symmetry of thephotoresist material.

[0057] The cross-sections of the substantially vertical side surfaces130 illustrated in FIGS. 6 and 8 are capable of being formed by thehalf-tone mask 136. FIG. 8 is also capable of being formed by either theintentionally misfocused light technique or the pre-etch hard baketechnique.

[0058] The cross-section of the sloped side surfaces 130 a illustratedin FIG. 7 is capable of being formed by intentionally misfocused lighton the side surfaces, the mask 137, or the pre-etch hard bake. In oneembodiment, using any of these three methods for forming the sloped sidesurfaces 130 a, the end surfaces 126 are able to be beveled using thesame method at the same time.

[0059] While the present invention has been disclosed with reference tothe foregoing specification and the preferred embodiment shown in thedrawings and described above, it will be apparent to those skilled inthe art that changes in form and detail may be made therein withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

[0060] We claim:

1. A heating element of a printhead comprising: a substrate; aconductive layer deposited over the substrate; and a resistive layerdeposited over and in electrical contact with the conductive layer. 2.The heating element of claim 1 further comprising a resistor formed ofthe resistive material, wherein the resistor couples sections of theconductive material.
 3. The heating element of claim 1 wherein theconductive layer has a first section and a second section that isdiscontinuous with the first section, and the resistive layer isdeposited over the conductive layer in between the first and secondsections.
 4. The heating element of claim 1 wherein the conductive layerhas an opening, and beveled surfaces adjacent the opening, wherein theresistive layer is deposited over the opening and the beveled surfaces.5. The heating element of claim 1 further comprising a barrier layerdeposited in between the conductive layer and the substrate.
 6. Theheating element of claim 1 further comprising an insulating layerdeposited in between the conductive layer and the substrate.
 7. Theheating element of claim 1 further comprising at least one of titaniumand a titanium alloy layer deposited in between the conductive layer andthe substrate.
 8. A printhead comprising: a substrate; a conductivelayer deposited over the substrate; a resistive layer deposited over andin electrical contact with the conductive layer; and a top layerdeposited over the resistive layer, wherein the top layer has an orificethrough which fluid is capable of being ejected.
 9. The printhead ofclaim 8 wherein the conductive layer defines a conductive trace havingfirst and second sections, wherein the resistive layer defines aresistor that couples the first and second sections of the conductivetrace, wherein the orifice is formed substantially above the resistor.10. The printhead of claim 9 wherein each of the first and secondsections has an end surface and two opposing side surfaces, wherein theend surface of the first section faces the end surface of the secondsection, wherein the end surface of each section is beveled, wherein thetwo opposing side surfaces have an angle with the substrate that is oneof equal to and greater than the angle between the substrate and the endsurface.
 11. The printhead of claim 10 wherein the end surface has anangle between about 35 to 55 degrees with the substrate and the sidesurfaces have an angle between about 35 to 80 degrees with thesubstrate.
 12. The printhead of claim 9 wherein the conductor trace hasa top surface with a width, wherein a resistor width is substantiallythe same as the top surface width.
 13. The printhead of claim 9 whereinthe conductor trace has a top surface with a width, wherein a resistorwidth is greater than the top surface width, such that the resistorencapsulates opposing side surfaces of the conductor trace.
 14. A methodof fabricating a printhead comprising: depositing conductive materialover a substrate; etching the conductive material to define at least oneof a conductor trace and a resistor length; depositing resistivematerial over the conductor trace; and depositing a top layer over theresistive material, wherein the top layer has an orifice through whichfluid is capable of being ejected.
 15. The method of claim 14 furthercomprising depositing photoresist over the conductive material andphotomasking before etching the conductive material; and removing thephotoresist material before depositing the resistive material.
 16. Themethod of claim 14 further comprising: depositing photoresist over theresistive material and photomasking; etching the resistive material todefine a resistor width and a cap width on the conductor traces; andremoving the photoresist material.
 17. The method of claim 14 whereinthe conductor trace has first and second sections, wherein an endsurface of the first section faces an end surface of the second section,the method further comprising beveling the end surface of each section.18. The method of claim 17 further comprising forming the end surfaceusing photomasking techniques.
 19. The method of claim 16 furthercomprising encapsulating the conductor trace, wherein the cap width isgreater than a width of the conductor trace.
 20. The method of claim 19wherein the conductor trace has first and second sections, each sectionhaving an end surface and two opposing side surfaces, wherein the endsurface of the first section faces the end surface of the secondsection, the method further comprising covering the side surfaces of theconductor traces with the cap width.